Campaigners today attacked the decision to prosecute nine West African immigrants for rioting at Campsfield House detention centre after the trial dramatically collapsed.

The defendants protested their innocence from the start of the case, which followed a riot at the Langford Lane, Kidlington, centre last August involving about 50 detainees and causing £100,000 worth of damage.

The trial - which cost hundreds of thousands of pounds - ended abruptly at Oxford Crown Court yesterday when the prosecution decided to offer no more evidence.

Evan Harris, MP for Oxford West and Abingdon, now plans to question ministers about the case in the House of Commons.

He said: "The collapse of this trial is a further vindication of the criticisms that I and humanitarian organisations have made of the Government's detention policy and their running of Campsfield House.."

The trial ended before the prosecution had called all its witnesses, after two of the defendants broke down.

Stanley Nwaidike, 22, left the dock yesterday after a Group 4 officer gave evidence identifying him as carrying a dumbell during the riot. It emerged during cross-examination that it was the first time the officer, Simon Ballard, had mentioned his name, despite three police statements.

Judge David Morton Jack adjourned the trial for a few minutes after he was told Mr Nwaidike was in a very distressed state. Then Sambou Marong, 17, burst into tears, and moments later Nicholas Jarman QC, prosecuting, told the judge he would not offer any further evidence. He said: "The prosecution is based entirely on the eye-witnesses and their evidence. We on behalf of the prosecution have been evaluating that continually as the trial has been progressing and, having heard all that eye-witness evidence and taking it as a whole, we have concluded that no prosecution properly conducted could or should invite the jury to convict on that evidence." Judge Morton Jack directed the jury to find eight defendants - Mr Nwaidike, Mr Marong, Harrison Tubman, 19, John Quaquah, 32, Enahoro Esemuze, 26, Sunny Ozidede, 30, Edward Onabanjo Agora, 27, and Lucky Agbebaku, 28 - not guilty of riot and disorder. The ninth, a 17-year-old who cannot be named for legal reasons, was ruled unfit to stand trial last week because of psychological problems and was due to be formally acquitted today.

Three of the men - Mr Ozidede, Mr Agbebaku and Mr Onabanjo Agora - were released immediately. The others are still being detained while their immigration applications are considered.

Mr Ozidede said outside the court: "I'm relieved. We've said it before right from the beginning that it was false charges and fabricated evidence. The wrong people were identified for reasons that are best known to them but with that identification we spent ten months in prison mixed with murderers.

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